1. Field of the Invention
This invention relates to solar heating systems, and particularly to a new combination of an enclosure and an absorber or collector.
2. General Description of the Prior Art
In the past few years, and even before, many configurations of solar collectors have been proposed and some of them marketed. The principal problem today with solar heat is, as with most products, providing an acceptable balance between cost, effectiveness, and durability. The fact that no single configuration has really captured the market is an indication that optimum designs are yet to appear. Considering the known types, perhaps the most common one is the flat plate collector wherein a dark colored heat receiver is encased within an enclosure having a transparent or translucent face through which solar radiation directly impinges on the receiver and having a bottom side which is heavily insulated. Typically, the receiver contains a passageway or passageways through which a liquid, to be heated, is circulated. Depending upon the material through which the receiver is constructed, and thereby often its durability, a flat plate collector costs in the vicinity of $8.00 to $14.00 per square foot of active surface, with typical installation costs for a domestic hot water heater system running $800.00 to $2,000.00. This high cost is in part because of a typical requirement that there be a liquid-to-liquid heat exchanger to heat potable water and the use of a special fluid which flows between the heat receiver and the heat exchanger in order to avoid corrosion and deposits on the passageways of the heat receiver, which would render the receiver inoperative or ineffective after a relatively short period (in terms of the typical and expected life a heat system or even a hot water system of 5 to 15 years).
In an effort to solve some of the foregoing problems, it has heretofore been proposed that where the object is to heat water, a potable hot water tank itself be encased in a heat receiving enclosure, and that in addition to utilizing direct radiation from the sun, some reflected radiation be captured and furnished to the tank. One such system is illustrated in the September, 1976 issue of "Popular Science" magazine, starting on page 101. This system employs an elongated tank in an enclosure with an elongated front and with two of the sides forming a light transmissive trapizoid. The back side, with a reflective inner surface, is parallel to the front side, and the top and bottom sides are perpendicular to the plane of the other sides and are heavily insulated. A difficulty with this configuration is that for optimum performance, it must be adjusted in attitude for the latitude of the location and as a function of the altitude (varying with seasons) of the sun. Preferably, some azimuth changes should be made through the day, i.e., tracking of the sun, for best solar energy capture.
Considering the foregoing, it is an object of this invention to overcome the stated problems, and particularly to provide a collector which both directly heats potable water, is long-lasting, and is of a configuration which provides a substantial measure of angular compensation, enabling it to be constructed with a fixed orientation, and yet be of improved effectiveness despite significant variations in both azimuth and altitude (seasons and latitude) of the sun.